Carburettors provide for the mixing of gasoline and air for intake via a manifold into the cylinder heads of an internal combustion engine.
Typically gasoline is drawn by venturi effect driven by the suction caused by downward movement of the piston in the cylinders from a reservoir via one or more jets into the throat of the carburettor.
It is desired that the air intake develops an even distribution of vapourized fuel of appropriate density on entry into cylinders of the engine so that maximum efficiency of combustion can be achieved. That is an ideal aspired to in carburettored fuel systems that is never fully achieved despite considerable research and development in the field.
Typically direct fuel injections systems have become standard for fuel intake of many internal combustion engines and are considered by many to provide a better delivery of fuel. There are, however, circumstances where carburettored systems are still common in particular in certain classes of competitive racing events.